Depending on the retrieval method, \(R_{i}\)  can be the sparse retrieval score, the dense retrieval score, or the score after hybrid fusion.
This final fused score replaces \(r_{i}\)  as the relevance score for each context in the answer span scoring step.
For example, with fusion, the answer span scoring technique of [1]} becomes \(\textrm {softmax}(\beta \cdot \vec{r}+\gamma \cdot \vec{R})_i \cdot \textrm {softmax}(\vec{s_{i}})_j\) .
